A century after theories identified the prominent roles of sugars in dental caries etiology and the discovery of the beneficial effects of fluorides, carie remains a highly prevalent disease throughout childhood, including adolescence. Adolescents' greater independence and frequent exposure to sugared beverages (e.g., soda pop) appear to place them at greater risk than at younger ages. However, these caries incidence patterns and relationships with risk factors are poorly understood because there are few studies of caries incidence or risk factors among adolescent subjects. Since 1991, using a cohort recruited at birth, the ongoing Iowa Fluoride Study (IFS) has comprehensively assessed the relationships between dietary data and fluoride exposures and dental caries in individuals at ages 5, 9, and 13. As caries continues to be a significant disease in adolescents, the proposed study provides a unique opportunity to assess the effects of socio-demographic, dietary, fluoride, and other factors on the incidence of dental caries during adolescence from age 13 to 17 years in our cohort. The main objectives of this proposal are to 1) conduct detailed secondary analyses of patterns of dental caries of the permanent dentition at age 17 and caries incidence from 13 to 17, and 2) comprehensively examine the relationships among dental caries incidence from age 13 to 17 (and age 17 prevalence) and dietary, fluoride, prior caries experience, and socio-demographic factors. Multivariable analyses will assess the relationships between and interactions among caries outcomes (incidence/increments and prevalence/counts) and longitudinally-collected data on various dietary patterns, oral health behaviors, fluoride exposures, previous caries experience, socio-demographics, and other factors. We will then assess the consistency of our findings concerning caries risk factors for ages 13 to 17 with those from analyses of caries risk factors during earlier periods from ages 5 to 9 and 9 to 13. As studies involving recruitment and successful retention of a cohort from birth are extremely rare, the Iowa Fluoride Study offers a unique opportunity to study these relationships in unprecedented detail, enhancing our ability to develop effective adolescent caries prevention programs.